Key SQL Azure Database Differences

SQL Server DBAs and developers should find working with SQL Azure Database similar in many ways to working with SQL Server. However, there are notable differences. For high availability, SQL Azure keeps three copies of every database. These copies may be on other geographically dispersed SQL Azure servers.

Most SQL Server T-SQL statements, data types, and system stored procedures are supported in SQL Azure. However, there are some common features that your current applications may incorporate that SQL Azure doesn't support. Features not supported by SQL Azure Database include

SQLCLR

geospatial data types

image, text, and ntext data type

user-defined data types

Windows authentication

the USE statement

the OPENQUERY and OPENROWSET statements

the BACKUP and RESTORE statements

support for accessing system tables

Notably, SQL Azure supports these data types: xml; the new date, time, and datetime2; and varbinary(max). For more information SQL Azure and T-SQL, refer to the complete SQL Azure T-SQL Reference.